Internal consistency of the object relations and social cognition scales for the Thematic Apperception Test.

We examined 8 data sets to determine whether it is possible to attain acceptable levels of internal consistency (coefficient alpha) reliability for the 4 Object Relations and Social Cognition scales (ORSC; Westen, Lohr, Silk, Kerber, & Goodrich, 1989) for the Thematic Apperception Test (TAT; Murray, 1943) when cards are considered as items in a scale. Number of cards used in the data sets ranged from 4 to 10, and the Spearman-Brown prophecy formula was applied to estimate the number of cards that would be required to attain alpha levels of different magnitudes. The two more structural subscales (Complexity of Representations and Understanding of Social Causality) have somewhat higher consistencies than the two more affective ones (Affect Tone and Capacity for Emotional Investment and Moral Standards). The results suggest that the use of 10 to 12 cards provides internal consistencies of alpha > or = .70 across each of the 4 ORSC scales.